The players, always thinking several shots ahead, know exactly where the cue ball must end up to control their next move – or foil their rival’s.

So it seemed again this week, although matches at the Crucible aren’t often as noisy.

Nicola Sturgeon initiated the megaphone diplomacy with her surprise unveiling of plans to hold another independence referendum before spring, 2019.

I say surprise, not because the announcement was unexpected, but because of the timing.

Many had assumed the SNP leader would make it amid adoring crowds at the party conference or even further down the line.

But in a stroke of political genius that really upped the stakes, she swooped in when everyone’s back was turned.

Theresa May found herself trumped. And her government was caught off guard – an impression that was confirmed to me privately.

No. 10 swiftly denied the PM had planned to trigger Article 50 and formally begin Brexit talks on Tuesday, the day after the necessary legislation cleared parliament and, as it turned out, Ms Sturgeon’s intervention.

But that’s how it appeared, the First Minister forcing Mrs May to hit the pause button.

Angus Robertson then took up the baton with his good cop routine, insisting during both Mrs May’s EU summit statement and Prime Minister’s Questions that there was still time to make a deal.

While the Tory leader responded with fighting talk in the Commons, action to see and raise the First Minister’s play was clearly needed.

Three days after Ms Sturgeon threw down the gauntlet, The gloves came off.

“Now is not the time,” came Mrs May’s uncompromising reply.

A suitably clever reciprocation, she carefully avoided saying when the time would be right.

I feel I’ve used the word momentous a lot recently, but it’s certainly fitting for these two bold steps from a pair of usually cautious leaders – arguably the biggest gambles of their respective careers.

Ms Sturgeon would likely have to stand down if she lost a referendum campaign and Mrs May must be aware her refusal will fuel nationalist sentiment.

As the First Minister put it, March 16, 2017, could go down as the day the “fate of the union” was sealed.

Yet both risks were calculated.

I don’t doubt the SNP leader’s sincerity in wanting to put the question to the people again, but the PM’s knock-back could ultimately work in her favour.

Come 2021 – Ms Sturgeon’s office has accepted there may not be another poll until then – she may be in a stronger position, especially if Brexit talks haven’t gone well.

Meanwhile, the nationalists have a grievance to campaign on.

On the other hand, Mrs May – who wants to put “all our energies” into getting the right Brexit deal – seems to think time is on her side.

And she’s determined to make the most of any breathing space, pledging to put strengthening the union at the centre of her plan for Britain.